{"id":4819,"date":"2026-03-29T12:02:54","date_gmt":"2026-03-29T10:02:54","guid":{"rendered":"https:\/\/nicolaslouis.com\/wordpress\/?p=4819"},"modified":"2026-03-31T17:32:11","modified_gmt":"2026-03-31T15:32:11","slug":"virages-du-cyanotype-chimie-mecanismes-et-protocoles","status":"publish","type":"post","link":"https:\/\/nicolaslouis.com\/wordpress\/2026\/03\/29\/virages-du-cyanotype-chimie-mecanismes-et-protocoles\/","title":{"rendered":"Virages du cyanotype : chimie, m\u00e9canismes et protocoles"},"content":{"rendered":"\n

Le cyanotype ne se limite pas \u00e0 son bleu caract\u00e9ristique. Soumis \u00e0 des bains chimiques sp\u00e9cifiques, le bleu de Prusse \u2014 pigment de coordination form\u00e9 lors de l’exposition \u2014 peut \u00eatre partiellement ou totalement transform\u00e9, substituant ses ions fer par d’autres agents complexants, ou converti en compos\u00e9s enti\u00e8rement diff\u00e9rents. C’est ce qu’on appelle le virage.<\/p>\n\n\n\n

Chaque virage repose sur un m\u00e9canisme chimique distinct : hydrolyse en milieu alcalin, ch\u00e9lation ferro-tannique, \u00e9change ionique par des m\u00e9taux de transition, ou d\u00e9p\u00f4t de nanoparticules par r\u00e9duction de sels nobles. La teinte finale \u2014 du brun s\u00e9pia au vert-noir, de l’or chaud au violet \u2014 n’est pas un effet cosm\u00e9tique : elle refl\u00e8te directement la nature des nouveaux complexes form\u00e9s et leur interaction avec la structure cristalline du pigment r\u00e9siduel.<\/p>\n\n\n\n

Le tableau ci-dessous recense treize virages document\u00e9s, class\u00e9s par famille chimique. Pour chacun, vous trouverez l’agent actif, le m\u00e9canisme r\u00e9actionnel, les param\u00e8tres de protocole, et les points de vigilance pratiques. Les concentrations et dur\u00e9es indiqu\u00e9es sont des bases de travail ; elles devront \u00eatre ajust\u00e9es selon le papier, la densit\u00e9 du tirage et la temp\u00e9rature du bain.<\/p>\n\n\n\n

<\/p>\n\n\n\n

Br\u00e8ve histoire du cyanotype<\/h2>\n\n\n\n

Le cyanotype est invent\u00e9 en 1842 par le physicien et astronome britannique Sir John Herschel, qui cherche alors un moyen simple de reproduire ses notes scientifiques. Il d\u00e9couvre que deux sels de fer \u2014 le citrate ferrique ammoniacal et le ferricyanure de potassium \u2014 forment, sous l’action de la lumi\u00e8re ultraviolette, un pigment insoluble d’une stabilit\u00e9 remarquable : le bleu de Prusse (Fe\u2084[Fe(CN)\u2086]\u2083). Herschel n’est pas photographe ; il est chimiste, et c’est \u00e0 ce titre qu’il publie le proc\u00e9d\u00e9 la m\u00eame ann\u00e9e, le pla\u00e7ant imm\u00e9diatement dans le domaine public.<\/p>\n\n\n\n

C’est la botaniste britannique Anna Atkins (1799\u20131871) qui en per\u00e7oit la premi\u00e8re le potentiel documentaire. D\u00e8s 1843, elle utilise le proc\u00e9d\u00e9 d’Herschel pour r\u00e9aliser des photogrammes de sp\u00e9cimens d’algues marines, pos\u00e9s directement sur le papier sensibilis\u00e9. Elle publie ainsi les Photographs of British Algae: Cyanotype Impressions<\/em> \u2014 consid\u00e9r\u00e9 aujourd’hui comme le premier livre illustr\u00e9 par la photographie jamais produit. Anna Atkins ne se contente pas d’appliquer une technique : elle en fait un outil scientifique rigoureux, produisant plusieurs volumes au fil des ann\u00e9es, chacun documentant avec une pr\u00e9cision remarquable la morphologie des algues de la c\u00f4te britannique.<\/p>\n\n\n\n

Pendant plusieurs d\u00e9cennies, le cyanotype reste cantonn\u00e9 \u00e0 des usages techniques et industriels. Les architectes et ing\u00e9nieurs l’adoptent massivement pour la reproduction de plans de construction, donnant naissance au mot anglais blueprint<\/em> \u2014 litt\u00e9ralement \u00ab\u00a0plan bleu\u00a0\u00bb \u2014 encore utilis\u00e9 aujourd’hui dans de nombreuses langues pour d\u00e9signer un projet ou une strat\u00e9gie.<\/p>\n\n\n\n

Tomb\u00e9 en d\u00e9su\u00e9tude avec l’essor des proc\u00e9d\u00e9s argentiques puis des photocopieuses, le cyanotype conna\u00eet depuis les ann\u00e9es 1990 un retour continu dans le champ des proc\u00e9d\u00e9s alternatifs. Sa simplicit\u00e9 de mise en \u0153uvre, sa non-toxicit\u00e9 relative et la richesse de ses possibilit\u00e9s de virage chimique en font aujourd’hui l’un des proc\u00e9d\u00e9s de contact les plus pratiqu\u00e9s par les photographes et artistes contemporains \u2014 \u00e0 la fois point d’entr\u00e9e pour les d\u00e9butants et terrain d’exp\u00e9rimentation pour les tireurs les plus exigeants.<\/p>\n\n\n

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Anna Atkins algae cyanotype 1843 book, \u00ab\u00a0British Algae\u00a0\u00bb<\/figcaption><\/figure>\n<\/div>\n\n\n\n\n\n\n\nVirages du cyanotype<\/title>\n<link rel=\"preconnect\" href=\"https:\/\/fonts.googleapis.com\">\n<link href=\"https:\/\/fonts.googleapis.com\/css2?family=DM+Sans:wght@400;500;600&family=EB+Garamond:ital,wght@0,600;1,400&display=swap\" rel=\"stylesheet\">\n<style>\n:root {\n --c-bg: #ffffff;\n --c-surface: #ffffff;\n --c-border: #e2ddd6;\n --c-border-md: #cec8be;\n --c-text: #1a1714;\n --c-muted: #6b6560;\n --c-faint: #9c958d;\n --c-accent: #37658b;\n --c-accent-lt: #e8f0eb;\n --pill-org-bg: #fdf0d5; --pill-org-tx: #7a4e0a;\n --pill-min-bg: #e2f0eb; --pill-min-tx: #1a4a35;\n --pill-alc-bg: #f0e8f5; --pill-alc-tx: #5a2d7a;\n --pill-aci-bg: #fce8e8; --pill-aci-tx: #8a1f1f;\n --pill-oxa-bg: #e5e8f5; --pill-oxa-tx: #2a2d7a;\n --pill-pre-bg: #e8f0e2; --pill-pre-tx: #2a4a1a;\n --pill-post-bg:#e8eef5; --pill-post-tx: #1a3050;\n --font-body: 'EB Garamond', Georgia, serif;\n --font-ui: 'DM Sans', system-ui, sans-serif;\n --r: 10px;\n}\n*, *::before, *::after { box-sizing: border-box; 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color: var(--c-faint); font-style: italic; margin-top: 1px; }\n.var-effect {\n display: inline-flex; align-items: center; gap: 6px;\n font-size: 12px; font-weight: 500;\n color: var(--c-text);\n background: #f2ede6;\n border-radius: 5px; padding: 4px 10px;\n}\n.var-effect-dot {\n width: 9px; height: 9px;\n border-radius: 50%; flex-shrink: 0;\n border: 1px solid rgba(0,0,0,.12);\n}\n.var-meca {\n font-size: 13px; color: var(--c-muted);\n line-height: 1.6;\n border-top: 1px solid var(--c-border);\n padding-top: 8px;\n}\n\n\/* \u2500\u2500 Tableau eau\/support (cards mobiles) \u2500\u2500 *\/\n.data-card {\n background: var(--c-surface);\n border: 1px solid var(--c-border);\n border-radius: 8px;\n padding: 13px 14px;\n margin-bottom: 8px;\n}\n.data-card-head { display: flex; align-items: center; gap: 10px; margin-bottom: 8px; }\n.data-card-title { font-weight: 600; font-size: 14px; color: var(--c-accent); }\n.data-card-body { font-size: 13px; color: var(--c-muted); line-height: 1.6; }\n\n\/* \u2500\u2500 L\u00e9gende \u2500\u2500 *\/\n.cyano-legend {\n display: flex; flex-wrap: wrap; gap: 10px;\n margin-top: 20px; padding-top: 16px;\n border-top: 1px solid var(--c-border);\n font-size: 11px; color: var(--c-faint);\n align-items: center;\n}\n.legend-label { font-weight: 600; color: var(--c-muted); }\n.leg-item { display: flex; align-items: center; gap: 5px; }\n.leg-dot {\n width: 9px; height: 9px;\n border-radius: 2px; display: inline-block; flex-shrink: 0;\n}\n<\/style>\n<\/head>\n<body>\n\n<div class=\"cw\">\n\n <div class=\"cw-head\">\n <h2>Virages du cyanotype<\/h2>\n <p>M\u00e9canismes chimiques & protocoles<\/p>\n <\/div>\n\n <!-- Filtres scroll -->\n <div class=\"filters-scroll\">\n <button class=\"fbtn active\" onclick=\"filter('all',this)\">Tous<\/button>\n <button class=\"fbtn\" onclick=\"filter('organique',this)\">Organique<\/button>\n <button class=\"fbtn\" onclick=\"filter('mineral',this)\">Min\u00e9ral<\/button>\n <button class=\"fbtn\" onclick=\"filter('alcalin',this)\">Alcalin<\/button>\n <button class=\"fbtn\" onclick=\"filter('acide',this)\">Acide<\/button>\n <button class=\"fbtn\" onclick=\"filter('oxalique',this)\">Oxalate<\/button>\n <\/div>\n <div class=\"count-line\" id=\"count\">13 virages<\/div>\n\n <!-- \u2550\u2550 CARDS VIRAGES \u2550\u2550 -->\n <div class=\"cards-list\" id=\"cards-list\">\n\n <!-- 1 -->\n <div class=\"vcard\" data-cat=\"organique\">\n <button class=\"vcard-trigger\" onclick=\"toggle(this)\">\n <span class=\"v-swatch\" style=\"background:#4a3728\"><\/span>\n <span class=\"v-trigger-text\">\n <span class=\"v-name\">Tanin de th\u00e9 noir<\/span>\n <span class=\"v-tone\">Brun-noir chaud<\/span>\n <\/span>\n <span class=\"v-pill-wrap\">\n <span class=\"pill pill-org\">Organique<\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/span>\n <\/button>\n <div class=\"vcard-body\">\n <div class=\"vcard-grid\">\n <div class=\"vdata-block\">\n <div class=\"vdata-label\">Agent actif<\/div>\n <div class=\"vdata-agent\">Acide tannique, polyph\u00e9nols, th\u00e9aflavines<br><em>Camellia sinensis<\/em><\/div>\n <\/div>\n <div class=\"vdata-block\">\n <div class=\"vdata-label\">M\u00e9canisme chimique<\/div>\n <div class=\"vdata-val\">Les polyph\u00e9nols r\u00e9duisent partiellement Fe\u00b3\u207a \u2192 Fe\u00b2\u207a et pr\u00e9cipitent avec le bleu de Prusse r\u00e9siduel. Formation de ch\u00e9lates ferro-tanniques brun-rouge. Destruction partielle du pigment selon la dur\u00e9e d’immersion.<\/div>\n <\/div>\n <div class=\"vdata-block\">\n <div class=\"vdata-label\">Protocole<\/div>\n <div class=\"vdata-val\">Infusion forte (10 sachets\/L), 70\u201380 \u00b0C. Bain 5\u201320 min selon intensit\u00e9. Rin\u00e7age eau froide. Pas de blanchiment pr\u00e9alable n\u00e9cessaire.<\/div>\n <\/div>\n <div class=\"vdata-block\">\n <div class=\"vdata-label\">Remarques<\/div>\n <div class=\"vdata-note\">Tr\u00e8s accessible. R\u00e9sultat variable selon le th\u00e9 (Assam = plus tannique). Th\u00e9 vert \u2192 virage vert-kaki, moins intense.<\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n\n <!-- 2 -->\n <div class=\"vcard\" data-cat=\"organique\">\n <button class=\"vcard-trigger\" onclick=\"toggle(this)\">\n <span class=\"v-swatch\" style=\"background:#5c3d1e\"><\/span>\n <span class=\"v-trigger-text\">\n <span class=\"v-name\">Tanin de caf\u00e9<\/span>\n <span class=\"v-tone\">Brun s\u00e9pia profond<\/span>\n <\/span>\n <span class=\"v-pill-wrap\">\n <span class=\"pill pill-org\">Organique<\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/span>\n <\/button>\n <div class=\"vcard-body\">\n <div class=\"vcard-grid\">\n <div class=\"vdata-block\"><div class=\"vdata-label\">Agent actif<\/div><div class=\"vdata-agent\">Acide chlorog\u00e9nique, caf\u00e9ine, polyph\u00e9nols<br><em>Coffea arabica \/ robusta<\/em><\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">M\u00e9canisme chimique<\/div><div class=\"vdata-val\">L’acide chlorog\u00e9nique est plus r\u00e9ducteur que le tanin de th\u00e9 : conversion plus pouss\u00e9e vers les complexes ferro-tanniques bruns. Action plus agressive sur le bleu de Prusse. pH l\u00e9g\u00e8rement acide (~5).<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Protocole<\/div><div class=\"vdata-val\">Caf\u00e9 tr\u00e8s fort (espresso dilu\u00e9 ou cold brew concentr\u00e9). Bain \u00e0 temp\u00e9rature ambiante 10\u201330 min. Possible en deux passes pour intensifier.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Remarques<\/div><div class=\"vdata-note\">R\u00e9sultat tr\u00e8s \u00ab\u00a0vintage\u00a0\u00bb. Caf\u00e9 tr\u00e8s torr\u00e9fi\u00e9 = bain plus acide, virage plus agressif aux hautes lumi\u00e8res.<\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n <!-- 3 -->\n <div class=\"vcard\" data-cat=\"organique\">\n <button class=\"vcard-trigger\" onclick=\"toggle(this)\">\n <span class=\"v-swatch\" style=\"background:#6b2737\"><\/span>\n <span class=\"v-trigger-text\">\n <span class=\"v-name\">Tanin de vin rouge<\/span>\n <span class=\"v-tone\">Brun-rouge vineux<\/span>\n <\/span>\n <span class=\"v-pill-wrap\">\n <span class=\"pill pill-org\">Organique<\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/span>\n <\/button>\n <div class=\"vcard-body\">\n <div class=\"vcard-grid\">\n <div class=\"vdata-block\"><div class=\"vdata-label\">Agent actif<\/div><div class=\"vdata-agent\">Anthocyanes, acide tartrique, tanins condens\u00e9s<br><em>Vitis vinifera<\/em><\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">M\u00e9canisme chimique<\/div><div class=\"vdata-val\">Les anthocyanes se fixent sur les r\u00e9sidus ferriques. L’acide tartrique (pH ~3,5) provoque une hydrolyse partielle du bleu de Prusse. Double action : d\u00e9coloration partielle + reteinture par les pigments du vin.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Protocole<\/div><div class=\"vdata-val\">Vin non dilu\u00e9 ou dilu\u00e9 1:1. Bain ambiant 5\u201315 min. Hautes lumi\u00e8res blanchissent vite : surveiller. Rin\u00e7age soigneux \u00e0 l’eau claire.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Remarques<\/div><div class=\"vdata-note\">Tr\u00e8s al\u00e9atoire selon le c\u00e9page. R\u00e9sultats moins reproductibles mais effets uniques. Risque de taches si bain in\u00e9gal.<\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n <!-- 4 -->\n <div class=\"vcard\" data-cat=\"organique\">\n <button class=\"vcard-trigger\" onclick=\"toggle(this)\">\n <span class=\"v-swatch\" style=\"background:#3b2a1a\"><\/span>\n <span class=\"v-trigger-text\">\n <span class=\"v-name\">Tanin de noix<\/span>\n <span class=\"v-tone\">Brun tabac tr\u00e8s sombre<\/span>\n <\/span>\n <span class=\"v-pill-wrap\">\n <span class=\"pill pill-org\">Organique<\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/span>\n <\/button>\n <div class=\"vcard-body\">\n <div class=\"vcard-grid\">\n <div class=\"vdata-block\"><div class=\"vdata-label\">Agent actif<\/div><div class=\"vdata-agent\">Acide gallique, acide ellagique, juglone<br><em>Juglans regia, Quercus<\/em><\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">M\u00e9canisme chimique<\/div><div class=\"vdata-val\">La juglone est un naphthoquinone fortement r\u00e9ducteur : conversion quasi-totale Fe\u00b3\u207a\u2192Fe\u00b2\u207a, destruction pouss\u00e9e du bleu de Prusse. Les compos\u00e9s galliques pr\u00e9cipitent en brun-noir avec le fer r\u00e9siduel.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Protocole<\/div><div class=\"vdata-val\">D\u00e9coction de coques de noix (30 min \u00e9bullition), concentr\u00e9e. Bain chaud 50\u201360 \u00b0C, 10\u201330 min. Blanchiment pr\u00e9alable \u00e0 la soude possible pour virage total.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Remarques<\/div><div class=\"vdata-note\">Virage parmi les plus intenses. Donne des noirs profonds. Tache irr\u00e9versiblement les mains et le papier hors zone image.<\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n <!-- 5 -->\n <div class=\"vcard\" data-cat=\"organique\">\n <button class=\"vcard-trigger\" onclick=\"toggle(this)\">\n <span class=\"v-swatch\" style=\"background:#2c3d2a\"><\/span>\n <span class=\"v-trigger-text\">\n <span class=\"v-name\">Acide tannique pur<\/span>\n <span class=\"v-tone\">Vert-noir profond<\/span>\n <\/span>\n <span class=\"v-pill-wrap\">\n <span class=\"pill pill-org\">Organique<\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/span>\n <\/button>\n <div class=\"vcard-body\">\n <div class=\"vcard-grid\">\n <div class=\"vdata-block\"><div class=\"vdata-label\">Agent actif<\/div><div class=\"vdata-agent\">Gallotanin (haut PM), acide gallique<br><em>C\u2087\u2086H\u2085\u2082O\u2084\u2086 \u2014 noix de galle<\/em><\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">M\u00e9canisme chimique<\/div><div class=\"vdata-val\">L’acide tannique pur ch\u00e9late fortement Fe\u00b3\u207a et forme du tanate de fer (identique \u00e0 l’encre ferrogallique historique) : pr\u00e9cipit\u00e9 noir-verd\u00e2tre extr\u00eamement stable. R\u00e9action de complexation sans destruction totale du bleu de Prusse.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Protocole<\/div><div class=\"vdata-val\">Solution 1\u20135% dans eau distill\u00e9e. Bain ambiant 10\u201320 min. Virage graduel et tr\u00e8s contr\u00f4lable. Rin\u00e7age eau distill\u00e9e.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Remarques<\/div><div class=\"vdata-note\">Virage vert-noir le plus stable et archivistiquement fiable. Co\u00fbt plus \u00e9lev\u00e9 que th\u00e9\/caf\u00e9 mais r\u00e9sultat tr\u00e8s reproductible.<\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n <!-- 6 -->\n <div class=\"vcard\" data-cat=\"mineral\">\n <button class=\"vcard-trigger\" onclick=\"toggle(this)\">\n <span class=\"v-swatch\" style=\"background:#8b6914\"><\/span>\n <span class=\"v-trigger-text\">\n <span class=\"v-name\">Permanganate de potassium<\/span>\n <span class=\"v-tone\">Or-brun chaud<\/span>\n <\/span>\n <span class=\"v-pill-wrap\">\n <span class=\"pill pill-min\">Min\u00e9ral<\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/span>\n <\/button>\n <div class=\"vcard-body\">\n <div class=\"vcard-grid\">\n <div class=\"vdata-block\"><div class=\"vdata-label\">Agent actif<\/div><div class=\"vdata-agent\">Ion MnO\u2084\u207b (oxydant fort)<br><em>KMnO\u2084<\/em><\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">M\u00e9canisme chimique<\/div><div class=\"vdata-val\">Oxyde Fe\u00b2\u207a\u2192Fe\u00b3\u207a et d\u00e9grade les ligands cyanure du bleu de Prusse. Le MnO\u2082 brun pr\u00e9cipite en surface et se combine aux r\u00e9sidus ferriques pour former des oxydes mangan\u00e8se-fer brun-dor\u00e9s.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Protocole<\/div><div class=\"vdata-val\">Solution 0,5\u20132 g\/L eau distill\u00e9e. Bain ambiant, surveillance continue (2\u201310 min). Rin\u00e7age imm\u00e9diat + bain d’acide citrique pour stopper la r\u00e9action.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Remarques<\/div><div class=\"vdata-note\">Progression tr\u00e8s rapide. D\u00e9p\u00f4ts de MnO\u2082 possibles si bain trop concentr\u00e9. Tester sur chutes. Solution \u00e0 conserver \u00e0 l’abri de la lumi\u00e8re.<\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n <!-- 7 -->\n <div class=\"vcard\" data-cat=\"mineral\">\n <button class=\"vcard-trigger\" onclick=\"toggle(this)\">\n <span class=\"v-swatch\" style=\"background:#4a6741\"><\/span>\n <span class=\"v-trigger-text\">\n <span class=\"v-name\">Chlorure de cuivre<\/span>\n <span class=\"v-tone\">Vert-olive sombre<\/span>\n <\/span>\n <span class=\"v-pill-wrap\">\n <span class=\"pill pill-min\">Min\u00e9ral<\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/span>\n <\/button>\n <div class=\"vcard-body\">\n <div class=\"vcard-grid\">\n <div class=\"vdata-block\"><div class=\"vdata-label\">Agent actif<\/div><div class=\"vdata-agent\">Ions Cu\u00b2\u207a<br><em>CuCl\u2082<\/em><\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">M\u00e9canisme chimique<\/div><div class=\"vdata-val\">Les ions cuivre se substituent partiellement au fer par \u00e9change ionique dans la structure du bleu de Prusse. Formation de complexes cyanure de cuivre (CuCN) de teinte verte : m\u00e9tath\u00e8se partielle du r\u00e9seau de coordination.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Protocole<\/div><div class=\"vdata-val\">Solution 5\u201310 g\/L. Bain ambiant 10\u201320 min. Rin\u00e7age eau distill\u00e9e. Combinable avec un bain de tanin en s\u00e9quence pour un r\u00e9sultat olive-brun.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Remarques<\/div><div class=\"vdata-note\">R\u00e9sultats variables selon la concentration. Hautes lumi\u00e8res souvent bleut\u00e9es si bain trop court. D\u00e9chets Cu\u00b2\u207a \u00e0 traiter (toxique).<\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n <!-- 8 -->\n <div class=\"vcard\" data-cat=\"mineral\">\n <button class=\"vcard-trigger\" onclick=\"toggle(this)\">\n <span class=\"v-swatch\" style=\"background:#5d8a6a\"><\/span>\n <span class=\"v-trigger-text\">\n <span class=\"v-name\">CuSO\u2084 + ammoniaque<\/span>\n <span class=\"v-tone\">Vert turquoise-sauge<\/span>\n <\/span>\n <span class=\"v-pill-wrap\">\n <span class=\"pill pill-min\">Min\u00e9ral<\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/span>\n <\/button>\n <div class=\"vcard-body\">\n <div class=\"vcard-grid\">\n <div class=\"vdata-block\"><div class=\"vdata-label\">Agent actif<\/div><div class=\"vdata-agent\">Complexe [Cu(NH\u2083)\u2084]\u00b2\u207a<br><em>CuSO\u2084 \/ NH\u2083<\/em><\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">M\u00e9canisme chimique<\/div><div class=\"vdata-val\">Le complexe ammino-cuivre d\u00e9place CN\u207b dans le r\u00e9seau prussien. Double destruction : NH\u2083 hydrolyse partiellement le bleu de Prusse, Cu forme des complexes cyan-verts stables. R\u00e9action en milieu basique (pH ~9\u201310).<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Protocole<\/div><div class=\"vdata-val\">Bain A : CuSO\u2084 10 g\/L. Bain B : ammoniaque 5%. M\u00e9langer juste avant usage. Bain 5\u201315 min. Rin\u00e7age soigneux. Manipuler sous ventilation (vapeurs NH\u2083).<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Remarques<\/div><div class=\"vdata-note\">Produit des verts introuvables par d’autres m\u00e9thodes. Sensible \u00e0 la dur\u00e9e : trop long = perte de densit\u00e9. EPI obligatoires.<\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n <!-- 9 -->\n <div class=\"vcard\" data-cat=\"mineral\">\n <button class=\"vcard-trigger\" onclick=\"toggle(this)\">\n <span class=\"v-swatch\" style=\"background:#6b4c2a\"><\/span>\n <span class=\"v-trigger-text\">\n <span class=\"v-name\">Chlorure d’or<\/span>\n <span class=\"v-tone\">Brun-rouge \u00e0 violet<\/span>\n <\/span>\n <span class=\"v-pill-wrap\">\n <span class=\"pill pill-min\">Min\u00e9ral<\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/span>\n <\/button>\n <div class=\"vcard-body\">\n <div class=\"vcard-grid\">\n <div class=\"vdata-block\"><div class=\"vdata-label\">Agent actif<\/div><div class=\"vdata-agent\">Ions Au\u00b3\u207a (oxydant fort)<br><em>HAuCl\u2084 \u2014 acide t\u00e9trachloroaurique<\/em><\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">M\u00e9canisme chimique<\/div><div class=\"vdata-val\">Au\u00b3\u207a oxyde Fe\u00b2\u207a\u2192Fe\u00b3\u207a et l’or m\u00e9tallique (Au\u2070) se d\u00e9pose en nanoparticules dans la structure prussienne. Ces nanoparticules produisent un effet plasmon de surface g\u00e9n\u00e9rant des teintes rouge \u00e0 violet selon leur taille.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Protocole<\/div><div class=\"vdata-val\">Solution tr\u00e8s dilu\u00e9e : 0,1\u20130,5 g\/L. Bain court 2\u20135 min, surveillance \u00e9troite. Rin\u00e7age eau distill\u00e9e. Souvent pr\u00e9c\u00e9d\u00e9 d’un bain de tanin pour stabiliser.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Remarques<\/div><div class=\"vdata-note\">Virage le plus on\u00e9reux. R\u00e9sultats spectaculaires et tr\u00e8s stables. Teinte d\u00e9pend du pH et de la concentration.<\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n <!-- 10 -->\n <div class=\"vcard\" data-cat=\"alcalin\">\n <button class=\"vcard-trigger\" onclick=\"toggle(this)\">\n <span class=\"v-swatch\" style=\"background:#c8b89a\"><\/span>\n <span class=\"v-trigger-text\">\n <span class=\"v-name\">Soude \/ carbonate<\/span>\n <span class=\"v-tone\">Blanchiment pr\u00e9-virage<\/span>\n <\/span>\n <span class=\"v-pill-wrap\">\n <span class=\"pill pill-alc\">Alcalin<\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/span>\n <\/button>\n <div class=\"vcard-body\">\n <div class=\"vcard-grid\">\n <div class=\"vdata-block\"><div class=\"vdata-label\">Agent actif<\/div><div class=\"vdata-agent\">Ions OH\u207b (base forte \/ mod\u00e9r\u00e9e)<br><em>NaOH \/ Na\u2082CO\u2083<\/em><\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">M\u00e9canisme chimique<\/div><div class=\"vdata-val\">En milieu alcalin, le bleu de Prusse est instable : hydrolyse des liaisons Fe\u2013CN\u2013Fe avec formation de Fe(OH)\u2083 et lib\u00e9ration de CN\u207b. Utilis\u00e9 court et dilu\u00e9 comme pr\u00e9-blanchiment avant tanin pour un virage total et uniforme.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Protocole<\/div><div class=\"vdata-val\">Na\u2082CO\u2083 : 5\u201310 g\/L, ambiant, 1\u20135 min, surveillance continue. NaOH : beaucoup plus agressif, quelques secondes \u00e0 1 min max \u00e0 1\u20132 g\/L. Rin\u00e7age imm\u00e9diat et abondant.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Remarques<\/div><div class=\"vdata-note\">Utilis\u00e9 seul = destruction de l’image. En \u00e9tape de blanchiment avant tanin = virage beaucoup plus complet.<\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n <!-- 11 -->\n <div class=\"vcard\" data-cat=\"alcalin\">\n <button class=\"vcard-trigger\" onclick=\"toggle(this)\">\n <span class=\"v-swatch\" style=\"background:#3d2b1f\"><\/span>\n <span class=\"v-trigger-text\">\n <span class=\"v-name\">Bleach & tone<\/span>\n <span class=\"v-tone\">Brun-noir s\u00e9pia riche<\/span>\n <\/span>\n <span class=\"v-pill-wrap\">\n <span class=\"pill pill-alc\">Alcalin<\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/span>\n <\/button>\n <div class=\"vcard-body\">\n <div class=\"vcard-grid\">\n <div class=\"vdata-block\"><div class=\"vdata-label\">Agent actif<\/div><div class=\"vdata-agent\">OH\u207b puis polyph\u00e9nols (tanin)<br><em>Na\u2082CO\u2083 \u2192 bain tanin<\/em><\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">M\u00e9canisme chimique<\/div><div class=\"vdata-val\">\u00c9tape 1 : bain alcalin hydrolyse une fraction du bleu de Prusse, laisse un r\u00e9sidu ferrique amorphe Fe(OH)\u2083. \u00c9tape 2 : le tanin r\u00e9agit avec Fe\u00b3\u207a r\u00e9siduel et forme des complexes ferro-tanniques (tanate de fer) tr\u00e8s stables, noir \u00e0 brun.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Protocole<\/div><div class=\"vdata-val\">Blanchiment Na\u2082CO\u2083 5 g\/L, 1\u20133 min. Rin\u00e7age 5 min eau courante. Bain tanin fort (th\u00e9, caf\u00e9, noix) 10\u201320 min. Rin\u00e7age final. S\u00e9chage plat.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Remarques<\/div><div class=\"vdata-note\">Technique de r\u00e9f\u00e9rence pour les bruns profonds. La dur\u00e9e du blanchiment d\u00e9termine l’intensit\u00e9.<\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n <!-- 12 -->\n <div class=\"vcard\" data-cat=\"acide\">\n <button class=\"vcard-trigger\" onclick=\"toggle(this)\">\n <span class=\"v-swatch\" style=\"background:#1a3a5c\"><\/span>\n <span class=\"v-trigger-text\">\n <span class=\"v-name\">Acide citrique<\/span>\n <span class=\"v-tone\">Bleu stabilis\u00e9<\/span>\n <\/span>\n <span class=\"v-pill-wrap\">\n <span class=\"pill pill-aci\">Acide<\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/span>\n <\/button>\n <div class=\"vcard-body\">\n <div class=\"vcard-grid\">\n <div class=\"vdata-block\"><div class=\"vdata-label\">Agent actif<\/div><div class=\"vdata-agent\">H\u207a doux + ch\u00e9lation citrate<br><em>C\u2086H\u2088O\u2087<\/em><\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">M\u00e9canisme chimique<\/div><div class=\"vdata-val\">N’attaque pas le bleu de Prusse mais le stabilise en abaissant le pH (3,5\u20134). Ch\u00e9late les ions Fe\u00b3\u207a libres en surface, \u00e9limine les voiles jaun\u00e2tres post-lavage. Virage tr\u00e8s subtil, surtout un bain de finition.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Protocole<\/div><div class=\"vdata-val\">5\u201310 g\/L dans eau distill\u00e9e. Bain final de 2\u20135 min apr\u00e8s lavage. Peut \u00eatre int\u00e9gr\u00e9 directement \u00e0 l’eau de rin\u00e7age habituelle.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Remarques<\/div><div class=\"vdata-note\">Surtout utilis\u00e9 comme bain de stabilisation post-virage. Pr\u00e9vient le jaunissement des blancs \u00e0 long terme.<\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n <!-- 13 -->\n <div class=\"vcard\" data-cat=\"oxalique\">\n <button class=\"vcard-trigger\" onclick=\"toggle(this)\">\n <span class=\"v-swatch\" style=\"background:#1d4a7a\"><\/span>\n <span class=\"v-trigger-text\">\n <span class=\"v-name\">Oxalate de potassium<\/span>\n <span class=\"v-tone\">Bleu de Prusse intense<\/span>\n <\/span>\n <span class=\"v-pill-wrap\">\n <span class=\"pill pill-oxa\">Oxalate<\/span>\n <svg class=\"chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" stroke-linecap=\"round\"><polyline points=\"6 9 12 15 18 9\"\/><\/svg>\n <\/span>\n <\/button>\n <div class=\"vcard-body\">\n <div class=\"vcard-grid\">\n <div class=\"vdata-block\"><div class=\"vdata-label\">Agent actif<\/div><div class=\"vdata-agent\">Ion oxalate C\u2082O\u2084\u00b2\u207b (ch\u00e9lateur Fe)<br><em>K\u2082C\u2082O\u2084<\/em><\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">M\u00e9canisme chimique<\/div><div class=\"vdata-val\">R\u00e9agit avec l’exc\u00e8s de sel ferrique non converti en surface. Formation d’oxalate ferrique soluble, \u00e9limin\u00e9 au rin\u00e7age. R\u00e9v\u00e8le un bleu plus pur, dense et sans voile. L\u00e9g\u00e8re compaction du r\u00e9seau de coordination.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Protocole<\/div><div class=\"vdata-val\">Solution 30\u201350 g\/L eau distill\u00e9e. Bain imm\u00e9diatement apr\u00e8s exposition et premier rin\u00e7age (avant s\u00e9chage). 2\u20135 min ambiant. Rin\u00e7age eau distill\u00e9e.<\/div><\/div>\n <div class=\"vdata-block\"><div class=\"vdata-label\">Remarques<\/div><div class=\"vdata-note\">Technique issue du proc\u00e9d\u00e9 platine\/Van Dyke. Donne le bleu le plus pur. Tr\u00e8s efficace contre les voiles dans les hautes lumi\u00e8res. Toxique : gants obligatoires.<\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n <\/div><!-- \/cards-list -->\n\n <!-- \u2550\u2550 SECTION 2 : Application directe \u2550\u2550 -->\n <div class=\"section-head\">\n <h3>R\u00e9actions par application directe<\/h3>\n <p>Avant exposition ou apr\u00e8s rin\u00e7age<\/p>\n <\/div>\n <p class=\"section-intro\">Ces substances agissent <em>avant<\/em> la photopolym\u00e9risation (modification locale du pH sur le papier sensibilis\u00e9) ou <em>apr\u00e8s<\/em> le rin\u00e7age (sur le bleu de Prusse d\u00e9j\u00e0 form\u00e9). Effets moins reproductibles que les virages en bain, mais interventions localis\u00e9es possibles.<\/p>\n\n <div class=\"subsection-label\">Avant exposition<\/div>\n\n <div class=\"var-card\">\n <div class=\"var-card-head\">\n <span class=\"var-swatch\" style=\"background:#1a2e50\"><\/span>\n <div><div class=\"var-name\">Vinaigre blanc<\/div><div class=\"var-agent\">Acide ac\u00e9tique ~5% \u2014 CH\u2083COOH<\/div><\/div>\n <\/div>\n <span class=\"pill pill-pre\">Pr\u00e9-exposition<\/span>\n <div class=\"var-effect\"><span class=\"var-effect-dot\" style=\"background:#1a2e50\"><\/span>Bleu plus sombre & satur\u00e9<\/div>\n <div class=\"var-meca\">L’acide ac\u00e9tique abaisse le pH local. En milieu l\u00e9g\u00e8rement acide, la formation du bleu de Prusse lors de l’exposition est favoris\u00e9e : la r\u00e9action Fe\u00b3\u207a + [Fe(CN)\u2086]\u2074\u207b \u2192 bleu de Prusse est plus compl\u00e8te, produisant un pigment plus dense dans les zones trait\u00e9es.<\/div>\n <\/div>\n\n <div class=\"var-card\">\n <div class=\"var-card-head\">\n <span class=\"var-swatch\" style=\"background:#c8c8a0\"><\/span>\n <div><div class=\"var-name\">Jus de citron<\/div><div class=\"var-agent\">Acide citrique + ascorbate<\/div><\/div>\n <\/div>\n <span class=\"pill pill-pre\">Pr\u00e9-exposition<\/span>\n <div class=\"var-effect\"><span class=\"var-effect-dot\" style=\"background:#c8c8a0\"><\/span>\u00c9claircissement local<\/div>\n <div class=\"var-meca\">L’acide ascorbique r\u00e9duit partiellement Fe\u00b3\u207a en Fe\u00b2\u207a avant m\u00eame l’exposition, appauvrissant le sel ferrique disponible. Les zones trait\u00e9es forment moins de bleu de Prusse \u2192 effet de r\u00e9serve partielle.<\/div>\n <\/div>\n\n <div class=\"var-card\">\n <div class=\"var-card-head\">\n <span class=\"var-swatch\" style=\"background:#c0ccd8\"><\/span>\n <div><div class=\"var-name\">Sel (NaCl)<\/div><div class=\"var-agent\">Chlorure de sodium<\/div><\/div>\n <\/div>\n <span class=\"pill pill-pre\">Pr\u00e9-exposition<\/span>\n <div class=\"var-effect\"><span class=\"var-effect-dot\" style=\"background:#c0ccd8\"><\/span>Textures cristallis\u00e9es<\/div>\n <div class=\"var-meca\">Les cristaux de NaCl perturbent m\u00e9caniquement la couche sensible lors du s\u00e9chage. Les ions Cl\u207b peuvent former du FeCl\u2083 local qui interf\u00e8re avec la cin\u00e9tique de formation du bleu de Prusse, cr\u00e9ant des zones \u00e0 texture irr\u00e9guli\u00e8re et granulaire.<\/div>\n <\/div>\n\n <div class=\"var-card\">\n <div class=\"var-card-head\">\n <span class=\"var-swatch\" style=\"background:#6b4a5a\"><\/span>\n <div><div class=\"var-name\">Vin rouge<\/div><div class=\"var-agent\">Anthocyanes + acide tartrique<\/div><\/div>\n <\/div>\n <span class=\"pill pill-pre\">Pr\u00e9-exposition<\/span>\n <div class=\"var-effect\"><span class=\"var-effect-dot\" style=\"background:#6b4a5a\"><\/span>Rouge-violet \/ gris<\/div>\n <div class=\"var-meca\">Les anthocyanes se fixent sur les fibres avant exposition. L’acide tartrique (pH ~3,5) modifie localement la chimie du bain ferrique. Apr\u00e8s rin\u00e7age, les anthocyanes r\u00e9siduels co-existent avec le bleu de Prusse et produisent des tons violets ou gris.<\/div>\n <\/div>\n\n <div class=\"var-card\">\n <div class=\"var-card-head\">\n <span class=\"var-swatch\" style=\"background:#7a7a28\"><\/span>\n <div><div class=\"var-name\">Curcuma<\/div><div class=\"var-agent\">Curcumine \u2014 C\u2082\u2081H\u2082\u2080O\u2086<\/div><\/div>\n <\/div>\n <span class=\"pill pill-pre\">Pr\u00e9-exposition<\/span>\n <div class=\"var-effect\"><span class=\"var-effect-dot\" style=\"background:#7a7a28\"><\/span>Jaune-verd\u00e2tre<\/div>\n <div class=\"var-meca\">La curcumine est un ch\u00e9lateur naturel des ions Fe\u00b3\u207a : elle forme des complexes curcumine-fer jaune-orange qui se substituent partiellement au bleu de Prusse dans les zones trait\u00e9es.<\/div>\n <\/div>\n\n <div class=\"subsection-label\">Apr\u00e8s rin\u00e7age<\/div>\n\n <div class=\"var-card\">\n <div class=\"var-card-head\">\n <span class=\"var-swatch\" style=\"background:#0f2d5a\"><\/span>\n <div><div class=\"var-name\">Eau oxyg\u00e9n\u00e9e (H\u2082O\u2082)<\/div><div class=\"var-agent\">Peroxyde d’hydrog\u00e8ne 3\u20136%<\/div><\/div>\n <\/div>\n <span class=\"pill pill-post\">Post-rin\u00e7age<\/span>\n <div class=\"var-effect\"><span class=\"var-effect-dot\" style=\"background:#0f2d5a\"><\/span>Bleu tr\u00e8s satur\u00e9 \u2014 imm\u00e9diat<\/div>\n <div class=\"var-meca\">H\u2082O\u2082 convertit instantan\u00e9ment tout le Fe\u00b2\u207a r\u00e9siduel en Fe\u00b3\u207a, achevant la formation du bleu de Prusse en quelques secondes. Sans lui, l’oxydation atmosph\u00e9rique (O\u2082 de l’air) r\u00e9alise la m\u00eame r\u00e9action en 12 \u00e0 24 heures.<\/div>\n <\/div>\n\n <!-- \u2550\u2550 SECTION 3 : Eau & support \u2550\u2550 -->\n <div class=\"section-head\">\n <h3>Eau de rin\u00e7age & support<\/h3>\n <p>Param\u00e8tres souvent sous-estim\u00e9s<\/p>\n <\/div>\n\n <div class=\"subsection-label\">Qualit\u00e9 de l’eau<\/div>\n\n <div class=\"data-card\">\n <div class=\"data-card-head\"><span class=\"var-swatch\" style=\"background:#0f2d5a\"><\/span><div class=\"data-card-title\">Eau distill\u00e9e<\/div><\/div>\n <div class=\"var-effect\" style=\"margin-bottom:8px\"><span class=\"var-effect-dot\" style=\"background:#0f2d5a\"><\/span>Bleu pur & satur\u00e9<\/div>\n <div class=\"data-card-body\">Absence d’ions parasites. Le r\u00e9seau cristallin du bleu de Prusse se forme sans interf\u00e9rence. R\u00e9sultat le plus fid\u00e8le \u00e0 la chimie th\u00e9orique.<\/div>\n <\/div>\n\n <div class=\"data-card\">\n <div class=\"data-card-head\"><span class=\"var-swatch\" style=\"background:#8a8878\"><\/span><div class=\"data-card-title\">Eau calcaire<\/div><\/div>\n <div class=\"var-effect\" style=\"margin-bottom:8px\"><span class=\"var-effect-dot\" style=\"background:#8a8878\"><\/span>Couleurs ternes, voile mat<\/div>\n <div class=\"data-card-body\">Ca\u00b2\u207a et Mg\u00b2\u207a forment des carbonates et sels insolubles en surface du pigment. Ce d\u00e9p\u00f4t diffuse la lumi\u00e8re et att\u00e9nue la saturation apparente.<\/div>\n <\/div>\n\n <div class=\"data-card\">\n <div class=\"data-card-head\"><span class=\"var-swatch\" style=\"background:#1a2e50\"><\/span><div class=\"data-card-title\">Eau ferrugineuse<\/div><\/div>\n <div class=\"var-effect\" style=\"margin-bottom:8px\"><span class=\"var-effect-dot\" style=\"background:#1a2e50\"><\/span>Bleu renforc\u00e9<\/div>\n <div class=\"data-card-body\">Les ions Fe\u00b3\u207a suppl\u00e9mentaires s’int\u00e8grent au r\u00e9seau prussien lors du rin\u00e7age, densifiant localement le pigment.<\/div>\n <\/div>\n\n <div class=\"data-card\">\n <div class=\"data-card-head\"><span class=\"var-swatch\" style=\"background:#3a5a6a\"><\/span><div class=\"data-card-title\">Eau de mer<\/div><\/div>\n <div class=\"var-effect\" style=\"margin-bottom:8px\"><span class=\"var-effect-dot\" style=\"background:#3a5a6a\"><\/span>Bleu-gris, textures<\/div>\n <div class=\"data-card-body\">Forte concentration en NaCl, Mg\u00b2\u207a, Ca\u00b2\u207a, SO\u2084\u00b2\u207b. Comp\u00e9tition ionique complexe avec le r\u00e9seau prussien. Effets de texture et l\u00e9g\u00e8re d\u00e9saturation. R\u00e9sultats peu reproductibles mais caract\u00e9ristiques.<\/div>\n <\/div>\n\n <div class=\"subsection-label\">Type de support<\/div>\n\n <div class=\"data-card\">\n <div class=\"data-card-head\"><span class=\"var-swatch\" style=\"background:#0f2a55\"><\/span><div class=\"data-card-title\">Papier coton<\/div><\/div>\n <div class=\"var-effect\" style=\"margin-bottom:8px\"><span class=\"var-effect-dot\" style=\"background:#0f2a55\"><\/span>Bleu profond & dense<\/div>\n <div class=\"data-card-body\">Fibres cellulosiques longues, pH neutre \u00e0 l\u00e9g\u00e8rement acide. Surface d’ancrage dense pour le bleu de Prusse. Meilleure r\u00e9tention du pigment dans la trame.<\/div>\n <\/div>\n\n <div class=\"data-card\">\n <div class=\"data-card-head\"><span class=\"var-swatch\" style=\"background:#4a5a6a\"><\/span><div class=\"data-card-title\">Papier japonais<\/div><\/div>\n <div class=\"var-effect\" style=\"margin-bottom:8px\"><span class=\"var-effect-dot\" style=\"background:#4a5a6a\"><\/span>Bleu-gris d\u00e9satur\u00e9<\/div>\n <div class=\"data-card-body\">Fibres courtes et tr\u00e8s poreuses. La couche sensible p\u00e9n\u00e8tre en profondeur, dispersant le pigment dans l’\u00e9paisseur du papier. Moins de pigment en surface = bleu moins intense, tendance au gris.<\/div>\n <\/div>\n\n <div class=\"data-card\">\n <div class=\"data-card-head\"><span class=\"var-swatch\" style=\"background:#2a4a60\"><\/span><div class=\"data-card-title\">Tissu (coton, lin)<\/div><\/div>\n <div class=\"var-effect\" style=\"margin-bottom:8px\"><span class=\"var-effect-dot\" style=\"background:#2a4a60\"><\/span>Bleu diffus & textur\u00e9<\/div>\n <div class=\"data-card-body\">Structure tridimensionnelle de la trame cr\u00e9e des zones d’exposition in\u00e9gale. Le pigment se d\u00e9pose pr\u00e9f\u00e9rentiellement sur les cr\u00eates des fibres, produisant un bleu h\u00e9t\u00e9rog\u00e8ne \u00e0 la texture tr\u00e8s caract\u00e9ristique.<\/div>\n <\/div>\n\n <!-- L\u00e9gende -->\n <div class=\"cyano-legend\">\n <span class=\"legend-label\">Virages :<\/span>\n <span class=\"leg-item\"><span class=\"leg-dot\" style=\"background:var(--pill-org-bg);border:1px solid var(--pill-org-tx)\"><\/span><span style=\"color:var(--pill-org-tx);font-weight:500\">Organique<\/span><\/span>\n <span class=\"leg-item\"><span class=\"leg-dot\" style=\"background:var(--pill-min-bg);border:1px solid var(--pill-min-tx)\"><\/span><span style=\"color:var(--pill-min-tx);font-weight:500\">Min\u00e9ral<\/span><\/span>\n <span class=\"leg-item\"><span class=\"leg-dot\" style=\"background:var(--pill-alc-bg);border:1px solid var(--pill-alc-tx)\"><\/span><span style=\"color:var(--pill-alc-tx);font-weight:500\">Alcalin<\/span><\/span>\n <span class=\"leg-item\"><span class=\"leg-dot\" style=\"background:var(--pill-aci-bg);border:1px solid var(--pill-aci-tx)\"><\/span><span style=\"color:var(--pill-aci-tx);font-weight:500\">Acide<\/span><\/span>\n <span class=\"leg-item\"><span class=\"leg-dot\" style=\"background:var(--pill-oxa-bg);border:1px solid var(--pill-oxa-tx)\"><\/span><span style=\"color:var(--pill-oxa-tx);font-weight:500\">Oxalate<\/span><\/span>\n <\/div>\n\n<\/div>\n\n<script>\nfunction toggle(btn) {\n var card = btn.closest('.vcard');\n card.classList.toggle('open');\n}\n\nfunction filter(cat, btn) {\n document.querySelectorAll('.fbtn').forEach(function(b){ b.classList.remove('active'); });\n btn.classList.add('active');\n var cards = document.querySelectorAll('#cards-list .vcard');\n var n = 0;\n cards.forEach(function(c) {\n var show = cat === 'all' || c.dataset.cat === cat;\n c.style.display = show ? '' : 'none';\n if (show) n++;\n });\n document.getElementById('count').textContent = n + ' virage' + (n > 1 ? 's' : '');\n}\n<\/script>\n\n<\/body>\n<\/html>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"590\" height=\"753\" src=\"https:\/\/nicolaslouis.com\/wordpress\/wp-content\/uploads\/2026\/03\/John_Frederick_William_Herschel_-_Lady_with_a_harp_1842.jpg\" alt=\"\" class=\"wp-image-4830\" srcset=\"https:\/\/nicolaslouis.com\/wordpress\/wp-content\/uploads\/2026\/03\/John_Frederick_William_Herschel_-_Lady_with_a_harp_1842.jpg 590w, https:\/\/nicolaslouis.com\/wordpress\/wp-content\/uploads\/2026\/03\/John_Frederick_William_Herschel_-_Lady_with_a_harp_1842-235x300.jpg 235w\" sizes=\"auto, (max-width: 590px) 100vw, 590px\" \/><figcaption class=\"wp-element-caption\">Sir John Herschel (1842) Experimental cyanotype of an unidentified engraving of a lady with a harp, Museum of the History of Science<\/figcaption><\/figure>\n<\/div>\n\n\n<!DOCTYPE html>\n<html lang=\"fr\">\n<head>\n<meta charset=\"UTF-8\">\n<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\">\n<title>N\u00e9gatif num\u00e9rique pour cyanotype<\/title>\n<link rel=\"preconnect\" href=\"https:\/\/fonts.googleapis.com\">\n<link href=\"https:\/\/fonts.googleapis.com\/css2?family=DM+Sans:wght@400;500;600&family=EB+Garamond:ital,wght@0,600;1,400&display=swap\" rel=\"stylesheet\">\n<style>\n:root {\n --c-bg: #ffffff;\n --c-surface: #ffffff;\n --c-border: #e2ddd6;\n --c-border-md: #cec8be;\n --c-text: #1a1714;\n --c-muted: #6b6560;\n --c-faint: #9c958d;\n --c-accent: #37658b;\n --c-accent-lt: #e8f0eb;\n --font-body: 'EB Garamond', Georgia, serif;\n --font-ui: 'DM Sans', system-ui, sans-serif;\n --r: 10px;\n}\n*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }\n\n\/* \u2500\u2500 Wrapper \u2500\u2500 *\/\n.nn {\n background: var(--c-bg);\n border: 1px solid var(--c-border);\n border-radius: var(--r);\n padding: 20px 16px 24px;\n font-family: var(--font-ui);\n color: var(--c-text);\n max-width: 100%;\n}\n\n\/* \u2500\u2500 Header \u2500\u2500 *\/\n.nn-head { margin-bottom: 18px; padding-bottom: 16px; border-bottom: 1px solid var(--c-border); }\n.nn-head h2 {\n font-family: var(--font-body);\n font-size: 21px; font-weight: 600;\n color: var(--c-accent);\n letter-spacing: -0.01em;\n line-height: 1.2; margin-bottom: 4px;\n}\n.nn-head p { font-size: 13px; color: var(--c-faint); font-style: italic; }\n\n\/* \u2500\u2500 Nav scroll \u2500\u2500 *\/\n.steps-scroll {\n display: flex; gap: 7px;\n overflow-x: auto; padding-bottom: 8px;\n margin-bottom: 18px;\n scrollbar-width: none;\n -webkit-overflow-scrolling: touch;\n}\n.steps-scroll::-webkit-scrollbar { display: none; }\n.snav {\n display: flex; align-items: center; gap: 6px;\n font-family: var(--font-ui);\n font-size: 13px; font-weight: 500;\n padding: 7px 14px 7px 9px;\n border-radius: 20px;\n border: 1px solid var(--c-border-md);\n background: transparent; color: var(--c-muted);\n cursor: pointer; white-space: nowrap; flex-shrink: 0;\n transition: all .15s;\n -webkit-tap-highlight-color: transparent;\n}\n.snav.active { background: var(--c-accent); border-color: var(--c-accent); color: #fff; }\n.snav-num {\n width: 20px; height: 20px; border-radius: 50%;\n background: rgba(0,0,0,.08);\n display: flex; align-items: center; justify-content: center;\n font-size: 10px; font-weight: 700; flex-shrink: 0;\n}\n.snav.active .snav-num { background: rgba(255,255,255,.25); }\n\n\/* \u2500\u2500 Panels \u2500\u2500 *\/\n.step-panel { display: none; }\n.step-panel.active { display: flex; flex-direction: column; gap: 20px; }\n\n\/* \u2500\u2500 Titres \u00e9tapes \u2500\u2500 *\/\n.step-title {\n font-family: var(--font-body);\n font-size: 19px; font-weight: 600;\n color: var(--c-accent);\n line-height: 1.25; margin-bottom: 10px;\n}\n.step-intro {\n font-size: 14px; color: var(--c-text);\n line-height: 1.65; margin-bottom: 16px;\n}\n\n\/* \u2500\u2500 Sections label \u2500\u2500 *\/\n.slabel {\n font-size: 10px; font-weight: 600;\n letter-spacing: .07em; text-transform: uppercase;\n color: var(--c-muted); margin-bottom: 8px;\n}\n\n\/* \u2500\u2500 Param\u00e8tres rows \u2500\u2500 *\/\n.params { display: flex; flex-direction: column; gap: 8px; margin-bottom: 14px; }\n.prow {\n display: flex; align-items: flex-start; gap: 10px;\n background: var(--c-surface);\n border: 1px solid var(--c-border);\n border-radius: 8px; padding: 11px 12px;\n}\n.picon {\n width: 30px; height: 30px; border-radius: 7px;\n background: var(--c-accent-lt);\n display: flex; align-items: center; justify-content: center;\n flex-shrink: 0;\n}\n.picon svg { width: 15px; height: 15px; stroke: var(--c-accent); fill: none; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }\n.picon-num { font-size: 13px; font-weight: 700; color: var(--c-accent); }\n.pkey { font-size: 11px; font-weight: 600; color: var(--c-muted); margin-bottom: 3px; }\n.pval { font-size: 13.5px; color: var(--c-text); line-height: 1.45; }\n.pval em { color: var(--c-muted); font-style: italic; font-size: 12px; }\n\n\/* \u2500\u2500 Tip box \u2500\u2500 *\/\n.tip {\n background: #f5f0e8;\n border-left: 3px solid var(--c-accent);\n border-radius: 0 6px 6px 0;\n padding: 11px 13px;\n font-size: 13px; color: var(--c-muted);\n line-height: 1.6; margin-top: 4px;\n}\n.tip strong { color: var(--c-accent); font-weight: 600; }\n\n\/* \u2500\u2500 Bloc visuel (card) \u2500\u2500 *\/\n.vcard {\n background: var(--c-surface);\n border: 1px solid var(--c-border);\n border-radius: 8px;\n padding: 16px;\n display: flex; flex-direction: column; gap: 12px;\n}\n.vlabel {\n font-size: 10px; font-weight: 600;\n letter-spacing: .07em; text-transform: uppercase;\n color: var(--c-faint);\n}\n\n\/* \u2500\u2500 Jauges densit\u00e9 \u2500\u2500 *\/\n.density-scale { display: flex; flex-direction: column; gap: 10px; }\n.drow { display: flex; align-items: center; gap: 10px; }\n.dlbl { font-size: 12px; color: var(--c-muted); width: 90px; flex-shrink: 0; }\n.dbar-wrap { flex: 1; height: 14px; background: #ede8e0; border-radius: 7px; overflow: hidden; }\n.dbar { height: 100%; border-radius: 7px; }\n.dval { font-size: 12px; font-weight: 600; color: var(--c-text); width: 32px; text-align: right; flex-shrink: 0; }\n\n\/* \u2500\u2500 R\u00e9solution dots \u2500\u2500 *\/\n.res-compare { display: flex; flex-direction: column; gap: 10px; }\n.rrow { display: flex; align-items: center; gap: 10px; }\n.rlbl { font-size: 12px; color: var(--c-muted); width: 70px; flex-shrink: 0; }\n.rdots { display: flex; gap: 2px; flex-wrap: wrap; flex: 1; }\n.rdot { width: 6px; height: 6px; border-radius: 1px; background: var(--c-accent); opacity: .2; }\n.rdot.on { opacity: 1; }\n.rnote { font-size: 11px; color: var(--c-faint); font-style: italic; }\n\n\/* \u2500\u2500 Film checklist \u2500\u2500 *\/\n.fchecks { display: flex; flex-direction: column; gap: 8px; }\n.fcheck {\n display: flex; align-items: flex-start; gap: 10px;\n padding: 10px 12px;\n border: 1px solid var(--c-border);\n border-radius: 7px; background: var(--c-bg);\n}\n.cico {\n width: 20px; height: 20px; border-radius: 50%;\n flex-shrink: 0; margin-top: 1px;\n display: flex; align-items: center; justify-content: center;\n}\n.cico.ok { background: #d4e8d8; }\n.cico.ko { background: #f0d8d8; }\n.cico svg { width: 10px; height: 10px; stroke-width: 2.5; stroke-linecap: round; stroke-linejoin: round; fill: none; }\n.cico.ok svg { stroke: #2a6a3a; }\n.cico.ko svg { stroke: #8a2a2a; }\n.ftxt { font-size: 13px; color: var(--c-text); line-height: 1.55; }\n.ftxt em { color: var(--c-muted); font-style: italic; font-size: 12px; }\n\n\/* \u2500\u2500 Courbe SVG \u2500\u2500 *\/\n.courbe-wrap { width: 100%; }\n.courbe-wrap svg { width: 100%; height: auto; display: block; }\n\n\/* \u2500\u2500 Table courbe \u2500\u2500 *\/\n.ctable-wrap {\n border: 1px solid var(--c-border);\n border-radius: 7px; overflow: hidden;\n}\n.ctable {\n width: 100%; border-collapse: collapse; font-size: 13px;\n}\n.ctable th {\n background: #f2ede6;\n font-size: 10px; font-weight: 600;\n letter-spacing: .05em; text-transform: uppercase;\n color: var(--c-muted);\n padding: 8px 10px; text-align: left;\n border-bottom: 1px solid var(--c-border-md);\n}\n.ctable td {\n padding: 9px 10px;\n border-bottom: 1px solid var(--c-border);\n color: var(--c-text); line-height: 1.4;\n}\n.ctable tr:last-child td { border-bottom: none; }\n.mono { font-family: monospace; font-weight: 600; color: var(--c-accent); }\n\n\/* \u2500\u2500 Contact steps \u2500\u2500 *\/\n.csteps { display: flex; flex-direction: column; gap: 8px; }\n.cstep {\n display: flex; align-items: flex-start; gap: 10px;\n padding: 11px 12px;\n border: 1px solid var(--c-border);\n border-radius: 7px; background: var(--c-bg);\n}\n.cnum {\n width: 24px; height: 24px; border-radius: 50%;\n background: var(--c-accent); color: #fff;\n font-size: 12px; font-weight: 600;\n display: flex; align-items: center; justify-content: center;\n flex-shrink: 0;\n}\n.ctxt { font-size: 13.5px; color: var(--c-text); line-height: 1.55; }\n.ctxt strong { color: var(--c-accent); font-weight: 600; }\n.ctxt em { color: var(--c-muted); font-style: italic; font-size: 12px; }\n\n\/* \u2500\u2500 Checklist verre \u2500\u2500 *\/\n.glass-checks { display: flex; flex-direction: column; gap: 7px; }\n.gcheck {\n display: flex; align-items: flex-start; gap: 9px;\n font-size: 13px; color: var(--c-text); line-height: 1.5;\n}\n.gdot {\n width: 18px; height: 18px; border-radius: 50%;\n flex-shrink: 0; margin-top: 1px;\n display: flex; align-items: center; justify-content: center;\n}\n.gdot.ok { background: #d4e8d8; }\n.gdot.ko { background: #f0d8d8; }\n.gdot svg { width: 9px; height: 9px; stroke-width: 2.5; stroke-linecap: round; stroke-linejoin: round; fill: none; }\n.gdot.ok svg { stroke: #2a6a3a; }\n.gdot.ko svg { stroke: #8a2a2a; }\n\n\/* \u2500\u2500 Nav bas \u2500\u2500 *\/\n.nn-nav {\n display: flex; justify-content: space-between; align-items: center;\n margin-top: 24px; padding-top: 16px;\n border-top: 1px solid var(--c-border);\n gap: 12px;\n}\n.nbtn {\n font-family: var(--font-ui);\n font-size: 13px; font-weight: 500;\n padding: 9px 18px; border-radius: 20px;\n border: 1px solid var(--c-border-md);\n background: transparent; color: var(--c-muted);\n cursor: pointer; transition: all .15s;\n -webkit-tap-highlight-color: transparent;\n flex-shrink: 0;\n}\n.nbtn:disabled { opacity: .3; cursor: default; }\n.nbtn.primary { background: var(--c-accent); border-color: var(--c-accent); color: #fff; }\n.nprog { font-size: 12px; color: var(--c-faint); text-align: center; }\n\n\/* \u2500\u2500 S\u00e9parateur interne vcard \u2500\u2500 *\/\n.vcard-sep { border-top: 1px solid var(--c-border); padding-top: 12px; }\n<\/style>\n<\/head>\n<body>\n\n<div class=\"nn\">\n\n <div class=\"nn-head\">\n <h2>Le n\u00e9gatif num\u00e9rique pour cyanotype<\/h2>\n <p>R\u00e9solution, densit\u00e9, courbe de correction, film & contact<\/p>\n <\/div>\n\n <!-- Nav scroll -->\n <div class=\"steps-scroll\">\n <button class=\"snav active\" onclick=\"goTo(0,this)\">\n <span class=\"snav-num\">1<\/span>R\u00e9solution & densit\u00e9\n <\/button>\n <button class=\"snav\" onclick=\"goTo(1,this)\">\n <span class=\"snav-num\">2<\/span>Film & impression\n <\/button>\n <button class=\"snav\" onclick=\"goTo(2,this)\">\n <span class=\"snav-num\">3<\/span>Courbe de correction\n <\/button>\n <button class=\"snav\" onclick=\"goTo(3,this)\">\n <span class=\"snav-num\">4<\/span>Contact & cadre presse\n <\/button>\n <\/div>\n\n <!-- \u2550\u2550 \u00c9TAPE 1 \u2550\u2550 -->\n <div class=\"step-panel active\" id=\"p0\">\n\n <div>\n <div class=\"step-title\">R\u00e9solution & densit\u00e9 du n\u00e9gatif<\/div>\n <p class=\"step-intro\">Le cyanotype exige un n\u00e9gatif sensiblement plus dense qu’un tirage argentique classique. \u00c0 l’\u0153il nu, un bon n\u00e9gatif num\u00e9rique doit para\u00eetre tr\u00e8s sombre \u2014 presque illisible dans les zones de hautes lumi\u00e8res. Cette densit\u00e9 compense la faible sensibilit\u00e9 aux UV du m\u00e9lange ferrique et garantit un contraste suffisant dans le tirage final.<\/p>\n\n <div class=\"slabel\">Param\u00e8tres recommand\u00e9s<\/div>\n <div class=\"params\">\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><rect x=\"3\" y=\"3\" width=\"18\" height=\"18\" rx=\"2\"\/><path d=\"M9 9h6M9 12h6M9 15h4\"\/><\/svg><\/div>\n <div><div class=\"pkey\">R\u00e9solution d’impression<\/div><div class=\"pval\">300 \u00e0 600 dpi <em>\u2014 360 dpi est un bon compromis universel<\/em><\/div><\/div>\n <\/div>\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><circle cx=\"12\" cy=\"12\" r=\"9\"\/><path d=\"M12 7v5l3 3\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Mode couleur du fichier<\/div><div class=\"pval\">Niveaux de gris 16 bits <em>\u2014 \u00e9vite la post\u00e9risation dans les tons moyens<\/em><\/div><\/div>\n <\/div>\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><path d=\"M12 3v18M3 12h18\"\/><circle cx=\"12\" cy=\"12\" r=\"4\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Densit\u00e9 cible (zones noires)<\/div><div class=\"pval\">D \u2265 2,8 \u00e0 3,2 <em>\u2014 mesurable au densitom\u00e8tre transmission<\/em><\/div><\/div>\n <\/div>\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><path d=\"M5 12h14M12 5l7 7-7 7\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Qualit\u00e9 d’impression<\/div><div class=\"pval\">Maximum \/ Photo <em>\u2014 ne jamais utiliser le mode brouillon<\/em><\/div><\/div>\n <\/div>\n <\/div>\n <div class=\"tip\"><strong>R\u00e8gle empirique :<\/strong> si le n\u00e9gatif pos\u00e9 sur une feuille blanche laisse lire le texte en dessous, il est trop clair. Les noirs doivent \u00eatre opaques \u00e0 la lumi\u00e8re visible.<\/div>\n <\/div>\n\n <!-- Visuel densit\u00e9 -->\n <div class=\"vcard\">\n <div class=\"vlabel\">Densit\u00e9 optique selon le type de n\u00e9gatif<\/div>\n <div class=\"density-scale\">\n <div class=\"drow\">\n <div class=\"dlbl\">Argentique<\/div>\n <div class=\"dbar-wrap\"><div class=\"dbar\" style=\"width:52%;background:#8a9ab0\"><\/div><\/div>\n <div class=\"dval\">1,8<\/div>\n <\/div>\n <div class=\"drow\">\n <div class=\"dlbl\">Platine \/ palladium<\/div>\n <div class=\"dbar-wrap\"><div class=\"dbar\" style=\"width:72%;background:#6a7a90\"><\/div><\/div>\n <div class=\"dval\">2,4<\/div>\n <\/div>\n <div class=\"drow\">\n <div class=\"dlbl\" style=\"font-weight:600;color:var(--c-accent)\">Cyanotype \u2605<\/div>\n <div class=\"dbar-wrap\"><div class=\"dbar\" style=\"width:90%;background:var(--c-accent)\"><\/div><\/div>\n <div class=\"dval\" style=\"color:var(--c-accent);font-weight:700\">3,0<\/div>\n <\/div>\n <div class=\"drow\">\n <div class=\"dlbl\" style=\"color:#a88\">Trop clair \u2717<\/div>\n <div class=\"dbar-wrap\"><div class=\"dbar\" style=\"width:30%;background:#c8c0b4\"><\/div><\/div>\n <div class=\"dval\" style=\"color:#a88\">1,0<\/div>\n <\/div>\n <\/div>\n <div class=\"vcard-sep\">\n <div class=\"vlabel\" style=\"margin-bottom:10px\">R\u00e9solution \u2014 impact sur le d\u00e9tail<\/div>\n <div class=\"res-compare\">\n <div class=\"rrow\">\n <div class=\"rlbl\" style=\"color:#a88\">150 dpi \u2717<\/div>\n <div class=\"rdots\" id=\"d150\"><\/div>\n <\/div>\n <div class=\"rrow\">\n <div class=\"rlbl\">300 dpi<\/div>\n <div class=\"rdots\" id=\"d300\"><\/div>\n <\/div>\n <div class=\"rrow\">\n <div class=\"rlbl\" style=\"color:var(--c-accent);font-weight:600\">600 dpi \u2605<\/div>\n <div class=\"rdots\" id=\"d600\"><\/div>\n <\/div>\n <\/div>\n <div class=\"rnote\" style=\"margin-top:6px\">Repr\u00e9sentation sch\u00e9matique de la densit\u00e9 de points par unit\u00e9 de surface<\/div>\n <\/div>\n <div style=\"font-size:11px;color:var(--c-faint);font-style:italic;border-top:1px solid var(--c-border);padding-top:10px;line-height:1.6;\">\n D = log\u2081\u2080(I\u2080\/I). Un n\u00e9gatif \u00e0 D=3,0 ne laisse passer que 0,1% de la lumi\u00e8re incidente dans les noirs.\n <\/div>\n <\/div>\n\n <\/div>\n\n <!-- \u2550\u2550 \u00c9TAPE 2 \u2550\u2550 -->\n <div class=\"step-panel\" id=\"p1\">\n\n <div>\n <div class=\"step-title\">Film transparent & impression<\/div>\n <p class=\"step-intro\">Le choix du film et du profil d’impression conditionne directement la densit\u00e9 maximale atteignable. Tous les films transparents jet d’encre ne sont pas \u00e9quivalents : la surface de r\u00e9ception de l’encre varie fortement d’une r\u00e9f\u00e9rence \u00e0 l’autre, avec un impact direct sur la densit\u00e9 optique dans les noirs et sur l’homog\u00e9n\u00e9it\u00e9 du d\u00e9p\u00f4t d’encre.<\/p>\n\n <div class=\"slabel\">Films recommand\u00e9s<\/div>\n <div class=\"params\">\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><rect x=\"4\" y=\"4\" width=\"16\" height=\"16\" rx=\"1\"\/><path d=\"M4 9h16M4 14h16M9 4v16\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Pictorico OHP \/ Ultra Premium<\/div><div class=\"pval\">R\u00e9f\u00e9rence professionnelle <em>\u2014 densit\u00e9 maximale, surface polyester matte<\/em><\/div><\/div>\n <\/div>\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><rect x=\"4\" y=\"4\" width=\"16\" height=\"16\" rx=\"1\"\/><path d=\"M4 9h16M4 14h16M9 4v16\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Fixxons \/ Imago transparency<\/div><div class=\"pval\">Bonne alternative <em>\u2014 l\u00e9g\u00e8rement moins dense mais plus accessible<\/em><\/div><\/div>\n <\/div>\n <\/div>\n\n <div class=\"slabel\">R\u00e9glages imprimante<\/div>\n <div class=\"params\">\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><path d=\"M6 9V4h12v5\"\/><rect x=\"2\" y=\"9\" width=\"20\" height=\"9\" rx=\"1\"\/><path d=\"M6 18v2h12v-2\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Type de papier dans le pilote<\/div><div class=\"pval\">Transparent jet d’encre <em>ou<\/em> Film mat <em>\u2014 jamais \u00ab\u00a0papier ordinaire\u00a0\u00bb<\/em><\/div><\/div>\n <\/div>\n <div class=\"prow\">\n <div class=\"picon\"><svg viewBox=\"0 0 24 24\"><path d=\"M12 2v4M12 18v4M4.93 4.93l2.83 2.83M16.24 16.24l2.83 2.83M2 12h4M18 12h4\"\/><\/svg><\/div>\n <div><div class=\"pkey\">Profil couleur<\/div><div class=\"pval\">Niveaux de gris + Noir uniquement <em>\u2014 d\u00e9sactiver la gestion des couleurs de l’imprimante<\/em><\/div><\/div>\n <\/div>\n <\/div>\n <div class=\"tip\"><strong>Sens d’impression :<\/strong> imprimer l’\u00e9mulsion c\u00f4t\u00e9 papier sensibilis\u00e9 (face \u00e0 face). Tester les deux faces du film pour identifier la face r\u00e9ceptrice.<\/div>\n <\/div>\n\n <!-- Visuel checklist film -->\n <div class=\"vcard\">\n <div class=\"vlabel\">Crit\u00e8res de s\u00e9lection du film<\/div>\n <div class=\"fchecks\">\n <div class=\"fcheck\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"ftxt\">Surface <strong>matte<\/strong> ou semi-matte \u2014 meilleure absorption de l’encre pigment\u00e9e <em>(\u00e9viter les films brillants)<\/em><\/div>\n <\/div>\n <div class=\"fcheck\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"ftxt\">Base <strong>polyester<\/strong> \u2014 stabilit\u00e9 dimensionnelle indispensable pour le contact<\/div>\n <\/div>\n <div class=\"fcheck\">\n <div class=\"cico ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\n <div class=\"ftxt\">Compatible <strong>encres pigment\u00e9es<\/strong> \u2014 meilleure densit\u00e9 et r\u00e9sistance UV que les encres colorant<\/div>\n <\/div>\n <div class=\"fcheck\">\n <div class=\"cico ko\"><svg viewBox=\"0 0 12 12\"><line x1=\"2\" y1=\"2\" x2=\"10\" y2=\"10\"\/><line x1=\"10\" y1=\"2\" x2=\"2\" y2=\"10\"\/><\/svg><\/div>\n <div class=\"ftxt\"><strong>Ac\u00e9tate de cellulose<\/strong> d\u00e9conseill\u00e9 \u2014 se d\u00e9forme \u00e0 l’humidit\u00e9, contact imparfait<\/div>\n <\/div>\n <div class=\"fcheck\">\n <div class=\"cico ko\"><svg viewBox=\"0 0 12 12\"><line x1=\"2\" y1=\"2\" x2=\"10\" y2=\"10\"\/><line x1=\"10\" y1=\"2\" x2=\"2\" y2=\"10\"\/><\/svg><\/div>\n <div class=\"ftxt\"><strong>R\u00e9troprojection standard<\/strong> (Avery, Office Depot) \u2014 surface trop lisse, densit\u00e9 insuffisante<\/div>\n <\/div>\n <\/div>\n <div class=\"tip\"><strong>Test de densit\u00e9 :<\/strong> imprimer un d\u00e9grad\u00e9 de gris 0\u2013100% et v\u00e9rifier que le 100% est opaque \u00e0 l’\u0153il devant une source lumineuse.<\/div>\n <\/div>\n\n <\/div>\n\n <!-- \u2550\u2550 \u00c9TAPE 3 \u2550\u2550 -->\n <div class=\"step-panel\" id=\"p2\">\n\n <div>\n <div class=\"step-title\">Courbe de correction \u2014 le S invers\u00e9<\/div>\n <p class=\"step-intro\">La r\u00e9ponse tonale du cyanotype est tr\u00e8s diff\u00e9rente de celle d’un tirage argentique ou d’un \u00e9cran. Sans correction, les ombres sont bouch\u00e9es et les hautes lumi\u00e8res br\u00fblent. La courbe de correction compense cette r\u00e9ponse non-lin\u00e9aire du proc\u00e9d\u00e9.<\/p>\n\n <div class=\"slabel\">Workflow de pr\u00e9paration<\/div>\n <div class=\"params\">\n <div class=\"prow\">\n <div class=\"picon\"><div class=\"picon-num\">01<\/div><\/div>\n <div><div class=\"pkey\">Convertir en niveaux de gris<\/div><div class=\"pval\">Mode Niveaux de gris 16 bits <em>\u2014 ou canal Luminosit\u00e9 depuis Lab<\/em><\/div><\/div>\n <\/div>\n <div class=\"prow\">\n <div class=\"picon\"><div class=\"picon-num\">02<\/div><\/div>\n <div><div class=\"pkey\">Inverser l’image<\/div><div class=\"pval\">Image \u2192 R\u00e9glages \u2192 N\u00e9gatif (Ctrl+I) <em>\u2014 on obtient le n\u00e9gatif<\/em><\/div><\/div>\n <\/div>\n <div class=\"prow\">\n <div class=\"picon\"><div class=\"picon-num\">03<\/div><\/div>\n <div><div class=\"pkey\">Appliquer la courbe de correction<\/div><div class=\"pval\">Courbe en S invers\u00e9 <em>\u2014 ombres \u00e9claircies, hautes lumi\u00e8res comprim\u00e9es<\/em><\/div><\/div>\n <\/div>\n <div class=\"prow\">\n <div class=\"picon\"><div class=\"picon-num\">04<\/div><\/div>\n <div><div class=\"pkey\">Aplatir et exporter<\/div><div class=\"pval\">TIFF 16 bits sans compression <em>\u2014 imprimer sans gestion des couleurs<\/em><\/div><\/div>\n <\/div>\n <\/div>\n <\/div>\n\n <!-- Courbe SVG pleine largeur -->\n <div class=\"vcard\">\n <div class=\"vlabel\">Courbe de correction \u2014 S invers\u00e9 pour cyanotype<\/div>\n <div class=\"courbe-wrap\">\n <svg viewBox=\"0 0 320 300\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" style=\"font-family:var(--font-ui)\">\n <rect x=\"40\" y=\"16\" width=\"260\" height=\"240\" fill=\"#f5f0e8\" rx=\"3\"\/>\n <line x1=\"40\" y1=\"76\" x2=\"300\" y2=\"76\" stroke=\"#cec8be\" stroke-width=\"0.5\" stroke-dasharray=\"3,3\"\/>\n <line x1=\"40\" y1=\"136\" x2=\"300\" y2=\"136\" stroke=\"#cec8be\" stroke-width=\"0.5\" stroke-dasharray=\"3,3\"\/>\n <line x1=\"40\" y1=\"196\" x2=\"300\" y2=\"196\" stroke=\"#cec8be\" stroke-width=\"0.5\" stroke-dasharray=\"3,3\"\/>\n <line x1=\"105\" y1=\"16\" x2=\"105\" y2=\"256\" stroke=\"#cec8be\" stroke-width=\"0.5\" stroke-dasharray=\"3,3\"\/>\n <line x1=\"170\" y1=\"16\" x2=\"170\" y2=\"256\" stroke=\"#cec8be\" stroke-width=\"0.5\" stroke-dasharray=\"3,3\"\/>\n <line x1=\"235\" y1=\"16\" x2=\"235\" y2=\"256\" stroke=\"#cec8be\" stroke-width=\"0.5\" stroke-dasharray=\"3,3\"\/>\n <line x1=\"40\" y1=\"256\" x2=\"300\" y2=\"16\" stroke=\"#cec8be\" stroke-width=\"1\" stroke-dasharray=\"5,4\"\/>\n <path d=\"M40,256 C80,198 120,185 170,155 C215,125 255,80 300,36\" fill=\"none\" stroke=\"#2c4a3e\" stroke-width=\"2.5\" stroke-linecap=\"round\"\/>\n <circle cx=\"105\" cy=\"210\" r=\"5\" fill=\"#2c4a3e\"\/>\n <circle cx=\"170\" cy=\"155\" r=\"5\" fill=\"#2c4a3e\"\/>\n <circle cx=\"235\" cy=\"94\" r=\"5\" fill=\"#2c4a3e\"\/>\n <line x1=\"105\" y1=\"210\" x2=\"138\" y2=\"194\" stroke=\"#2c4a3e\" stroke-width=\"0.8\"\/>\n <rect x=\"139\" y=\"180\" width=\"84\" height=\"28\" rx=\"3\" fill=\"#e8f0eb\"\/>\n <text x=\"181\" y=\"192\" text-anchor=\"middle\" font-size=\"9.5\" fill=\"#1a4a35\" font-weight=\"600\">Ombres \u00e9claircies<\/text>\n <text x=\"181\" y=\"204\" text-anchor=\"middle\" font-size=\"8.5\" fill=\"#2c4a3e\">25 \u2192 40 (ouverture)<\/text>\n <line x1=\"235\" y1=\"94\" x2=\"224\" y2=\"72\" stroke=\"#2c4a3e\" stroke-width=\"0.8\"\/>\n <rect x=\"148\" y=\"46\" width=\"90\" height=\"28\" rx=\"3\" fill=\"#e8f0eb\"\/>\n <text x=\"193\" y=\"58\" text-anchor=\"middle\" font-size=\"9.5\" fill=\"#1a4a35\" font-weight=\"600\">Hautes lumi\u00e8res<\/text>\n <text x=\"193\" y=\"70\" text-anchor=\"middle\" font-size=\"8.5\" fill=\"#2c4a3e\">75 \u2192 80 (compression)<\/text>\n <line x1=\"46\" y1=\"34\" x2=\"62\" y2=\"34\" stroke=\"#cec8be\" stroke-width=\"1\" stroke-dasharray=\"4,3\"\/>\n <text x=\"66\" y=\"38\" font-size=\"9\" fill=\"#9c958d\">lin\u00e9aire (r\u00e9f.)<\/text>\n <line x1=\"40\" y1=\"256\" x2=\"40\" y2=\"10\" stroke=\"#6b6560\" stroke-width=\"1.2\"\/>\n <line x1=\"40\" y1=\"256\" x2=\"306\" y2=\"256\" stroke=\"#6b6560\" stroke-width=\"1.2\"\/>\n <polygon points=\"40,10 37,18 43,18\" fill=\"#6b6560\"\/>\n <polygon points=\"306,256 298,253 298,259\" fill=\"#6b6560\"\/>\n <text x=\"170\" y=\"275\" text-anchor=\"middle\" font-size=\"10\" fill=\"#6b6560\">Entr\u00e9e (valeur originale)<\/text>\n <text x=\"14\" y=\"140\" text-anchor=\"middle\" font-size=\"10\" fill=\"#6b6560\" transform=\"rotate(-90,14,140)\">Sortie (n\u00e9gatif)<\/text>\n <text x=\"40\" y=\"268\" text-anchor=\"middle\" font-size=\"9\" fill=\"#9c958d\">0<\/text>\n <text x=\"105\" y=\"268\" text-anchor=\"middle\" font-size=\"9\" fill=\"#9c958d\">25<\/text>\n <text x=\"170\" y=\"268\" text-anchor=\"middle\" font-size=\"9\" fill=\"#9c958d\">50<\/text>\n <text x=\"235\" y=\"268\" text-anchor=\"middle\" font-size=\"9\" fill=\"#9c958d\">75<\/text>\n <text x=\"300\" y=\"268\" text-anchor=\"middle\" font-size=\"9\" fill=\"#9c958d\">100<\/text>\n <text x=\"34\" y=\"259\" text-anchor=\"end\" font-size=\"9\" fill=\"#9c958d\">0<\/text>\n <text x=\"34\" y=\"199\" text-anchor=\"end\" font-size=\"9\" fill=\"#9c958d\">25<\/text>\n <text x=\"34\" y=\"139\" text-anchor=\"end\" font-size=\"9\" fill=\"#9c958d\">50<\/text>\n <text x=\"34\" y=\"79\" text-anchor=\"end\" font-size=\"9\" fill=\"#9c958d\">75<\/text>\n <text x=\"34\" y=\"20\" text-anchor=\"end\" font-size=\"9\" fill=\"#9c958d\">100<\/text>\n <\/svg>\n <\/div>\n <div style=\"font-size:12px;color:var(--c-faint);font-style:italic;border-top:1px solid var(--c-border);padding-top:10px;line-height:1.6;\">\n La courbe passe au-dessus de la diagonale dans les basses valeurs (ombres ouvertes) et en dessous dans les hautes valeurs (lumi\u00e8res comprim\u00e9es). C’est l’inverse exact de la correction pour un tirage argentique.\n <\/div>\n <\/div>\n\n <!-- Table points de courbe -->\n <div>\n <div class=\"slabel\" style=\"margin-bottom:8px\">Points de courbe de r\u00e9f\u00e9rence<\/div>\n <div class=\"ctable-wrap\">\n <table class=\"ctable\">\n <thead>\n <tr>\n <th>Zone tonale<\/th>\n <th style=\"text-align:center\">Entr\u00e9e<\/th>\n <th style=\"text-align:center\">Sortie<\/th>\n <th>Effet<\/th>\n <\/tr>\n <\/thead>\n <tbody>\n <tr><td>Noirs profonds<\/td><td style=\"text-align:center\" class=\"mono\">0<\/td><td style=\"text-align:center\" class=\"mono\">0<\/td><td style=\"color:var(--c-muted);font-size:12px\">Conserv\u00e9s<\/td><\/tr>\n <tr><td>Ombres<\/td><td style=\"text-align:center\" class=\"mono\">25<\/td><td style=\"text-align:center\" class=\"mono\">40<\/td><td style=\"color:var(--c-muted);font-size:12px\">\u2191 Ouverture<\/td><\/tr>\n <tr><td>Tons moyens<\/td><td style=\"text-align:center\" class=\"mono\">50<\/td><td style=\"text-align:center\" class=\"mono\">52<\/td><td style=\"color:var(--c-muted);font-size:12px\">Zone neutre<\/td><\/tr>\n <tr><td>Hautes lumi\u00e8res<\/td><td style=\"text-align:center\" class=\"mono\">75<\/td><td style=\"text-align:center\" class=\"mono\">80<\/td><td style=\"color:var(--c-muted);font-size:12px\">\u2193 Compression<\/td><\/tr>\n <tr><td>Blancs<\/td><td style=\"text-align:center\" class=\"mono\">100<\/td><td style=\"text-align:center\" class=\"mono\">100<\/td><td style=\"color:var(--c-muted);font-size:12px\">Conserv\u00e9s<\/td><\/tr>\n <\/tbody>\n <\/table>\n <\/div>\n <div class=\"tip\" style=\"margin-top:10px\"><strong>\u00c0 calibrer :<\/strong> ces valeurs sont un point de d\u00e9part. La courbe finale d\u00e9pend du papier, de l’\u00e9mulsion, de la source UV et de la dur\u00e9e d’exposition. R\u00e9aliser une mire de gris (step wedge) \u00e0 chaque changement de variable.<\/div>\n <\/div>\n\n <\/div>\n\n <!-- \u2550\u2550 \u00c9TAPE 4 \u2550\u2550 -->\n <div class=\"step-panel\" id=\"p3\">\n\n <div>\n <div class=\"step-title\">Contact & cadre presse<\/div>\n <p class=\"step-intro\">La qualit\u00e9 du contact entre le n\u00e9gatif et le papier sensibilis\u00e9 est souvent la premi\u00e8re cause de cyanotypes \u00ab\u00a0mous\u00a0\u00bb. La lumi\u00e8re UV, m\u00eame tr\u00e8s l\u00e9g\u00e8rement diffus\u00e9e dans un espace d’air de quelques microns, suffit \u00e0 d\u00e9grader la nettet\u00e9 des d\u00e9tails fins et \u00e0 r\u00e9duire la gamme tonale.<\/p>\n\n <div class=\"slabel\">Montage \u2014 ordre des couches<\/div>\n <div class=\"csteps\">\n <div class=\"cstep\"><div class=\"cnum\">1<\/div><div class=\"ctxt\"><strong>Verre optique<\/strong> \u2014 3 \u00e0 4 mm, bords polis <em>(en haut, c\u00f4t\u00e9 source UV)<\/em><\/div><\/div>\n <div class=\"cstep\"><div class=\"cnum\">2<\/div><div class=\"ctxt\"><strong>N\u00e9gatif<\/strong> \u2014 face imprim\u00e9e vers le bas, en contact direct avec le papier<\/div><\/div>\n <div class=\"cstep\"><div class=\"cnum\">3<\/div><div class=\"ctxt\"><strong>Papier sensibilis\u00e9<\/strong> \u2014 face sensibilis\u00e9e vers le haut, au contact du n\u00e9gatif<\/div><\/div>\n <div class=\"cstep\"><div class=\"cnum\">4<\/div><div class=\"ctxt\"><strong>Fond rigide<\/strong> \u2014 carton \u00e9pais ou plaque MDF <em>(en bas, pour rigidit\u00e9)<\/em><\/div><\/div>\n <div class=\"cstep\"><div class=\"cnum\">5<\/div><div class=\"ctxt\"><strong>Pinces ou cadre presse<\/strong> \u2014 pression uniforme sur l’ensemble de la surface<\/div><\/div>\n <\/div>\n <div class=\"tip\" style=\"margin-top:14px\"><strong>Verre anti-reflet :<\/strong> le verre anti-reflet standard filtre une partie des UV. Pr\u00e9f\u00e9rer du verre blanc extra-clair (type Optiwhite) ou du verre optique non trait\u00e9.<\/div>\n <\/div>\n\n <!-- Sch\u00e9ma contact -->\n <div class=\"vcard\">\n <div class=\"vlabel\">Contact parfait vs imparfait<\/div>\n <svg viewBox=\"0 0 280 90\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" style=\"width:100%;font-family:var(--font-ui)\">\n <text x=\"70\" y=\"12\" text-anchor=\"middle\" font-size=\"9.5\" fill=\"#2c4a3e\" font-weight=\"600\">Contact parfait<\/text>\n <rect x=\"10\" y=\"18\" width=\"120\" height=\"10\" rx=\"2\" fill=\"#b0c8d8\" opacity=\".7\"\/>\n <text x=\"133\" y=\"27\" font-size=\"7.5\" fill=\"#6b6560\">Verre<\/text>\n <rect x=\"10\" y=\"30\" width=\"120\" height=\"5\" rx=\"1\" fill=\"#6b6560\" opacity=\".5\"\/>\n <text x=\"133\" y=\"37\" font-size=\"7.5\" fill=\"#6b6560\">N\u00e9gatif<\/text>\n <rect x=\"10\" y=\"37\" width=\"120\" height=\"9\" rx=\"1\" fill=\"#c8b89a\" opacity=\".6\"\/>\n <text x=\"133\" y=\"45\" font-size=\"7.5\" fill=\"#6b6560\">Papier<\/text>\n <line x1=\"30\" y1=\"8\" x2=\"30\" y2=\"46\" stroke=\"#854f0b\" stroke-width=\"1\" stroke-dasharray=\"2,1\"\/>\n <line x1=\"55\" y1=\"8\" x2=\"55\" y2=\"46\" stroke=\"#854f0b\" stroke-width=\"1\" stroke-dasharray=\"2,1\"\/>\n <line x1=\"80\" y1=\"8\" x2=\"80\" y2=\"46\" stroke=\"#854f0b\" stroke-width=\"1\" stroke-dasharray=\"2,1\"\/>\n <line x1=\"105\" y1=\"8\" x2=\"105\" y2=\"46\" stroke=\"#854f0b\" stroke-width=\"1\" stroke-dasharray=\"2,1\"\/>\n <rect x=\"10\" y=\"54\" width=\"120\" height=\"16\" rx=\"2\" fill=\"#1d4a7a\"\/>\n <text x=\"70\" y=\"65\" text-anchor=\"middle\" font-size=\"8.5\" fill=\"#fff\" font-weight=\"500\">D\u00e9tail net \u2014 bords francs<\/text>\n\n <text x=\"210\" y=\"12\" text-anchor=\"middle\" font-size=\"9.5\" fill=\"#8a2a2a\" font-weight=\"600\">Contact imparfait<\/text>\n <rect x=\"150\" y=\"18\" width=\"120\" height=\"10\" rx=\"2\" fill=\"#b0c8d8\" opacity=\".7\"\/>\n <rect x=\"150\" y=\"30\" width=\"120\" height=\"5\" rx=\"1\" fill=\"#6b6560\" opacity=\".5\"\/>\n <rect x=\"150\" y=\"35\" width=\"120\" height=\"4\" fill=\"#faf8f5\" opacity=\".9\"\/>\n <text x=\"210\" y=\"41\" text-anchor=\"middle\" font-size=\"7\" fill=\"#a88\">espace d’air<\/text>\n <rect x=\"150\" y=\"39\" width=\"120\" height=\"9\" rx=\"1\" fill=\"#c8b89a\" opacity=\".6\"\/>\n <line x1=\"170\" y1=\"8\" x2=\"163\" y2=\"48\" stroke=\"#854f0b\" stroke-width=\"1\" stroke-dasharray=\"2,1\" opacity=\".5\"\/>\n <line x1=\"170\" y1=\"8\" x2=\"177\" y2=\"48\" stroke=\"#854f0b\" stroke-width=\"1\" stroke-dasharray=\"2,1\" opacity=\".5\"\/>\n <line x1=\"195\" y1=\"8\" x2=\"188\" y2=\"48\" stroke=\"#854f0b\" stroke-width=\"1\" stroke-dasharray=\"2,1\" opacity=\".5\"\/>\n <line x1=\"220\" y1=\"8\" x2=\"220\" y2=\"48\" stroke=\"#854f0b\" stroke-width=\"1\" stroke-dasharray=\"2,1\" opacity=\".5\"\/>\n <line x1=\"245\" y1=\"8\" x2=\"252\" y2=\"48\" stroke=\"#854f0b\" stroke-width=\"1\" stroke-dasharray=\"2,1\" opacity=\".5\"\/>\n <rect x=\"150\" y=\"54\" width=\"120\" height=\"16\" rx=\"2\" fill=\"#4a5a70\"\/>\n <text x=\"210\" y=\"65\" text-anchor=\"middle\" font-size=\"8.5\" fill=\"#c8d0dc\" font-weight=\"500\">D\u00e9tail mou \u2014 contraste r\u00e9duit<\/text>\n <line x1=\"140\" y1=\"8\" x2=\"140\" y2=\"76\" stroke=\"#e2ddd6\" stroke-width=\"1\"\/>\n <\/svg>\n\n <div class=\"vcard-sep\">\n <div class=\"vlabel\" style=\"margin-bottom:10px\">Exigences du verre<\/div>\n <div class=\"glass-checks\">\n <div class=\"gcheck\"><div class=\"gdot ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>\u00c9paisseur 3\u20134 mm minimum (rigidit\u00e9)<\/div>\n <div class=\"gcheck\"><div class=\"gdot ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>Verre extra-clair \u2014 faible teneur en fer (type Optiwhite)<\/div>\n <div class=\"gcheck\"><div class=\"gdot ok\"><svg viewBox=\"0 0 12 12\"><polyline points=\"2,6 5,9 10,3\"\/><\/svg><\/div>Bords polis \u2014 pas de verre flott\u00e9 brut<\/div>\n <div class=\"gcheck\"><div class=\"gdot ko\"><svg viewBox=\"0 0 12 12\"><line x1=\"2\" y1=\"2\" x2=\"10\" y2=\"10\"\/><line x1=\"10\" y1=\"2\" x2=\"2\" y2=\"10\"\/><\/svg><\/div>\u00c9viter le verre feuillet\u00e9 (filtre les UV)<\/div>\n <div class=\"gcheck\"><div class=\"gdot ko\"><svg viewBox=\"0 0 12 12\"><line x1=\"2\" y1=\"2\" x2=\"10\" y2=\"10\"\/><line x1=\"10\" y1=\"2\" x2=\"2\" y2=\"10\"\/><\/svg><\/div>\u00c9viter le Plexiglas (filtre les UV < 380 nm)<\/div>\n <div class=\"gcheck\"><div class=\"gdot ko\"><svg viewBox=\"0 0 12 12\"><line x1=\"2\" y1=\"2\" x2=\"10\" y2=\"10\"\/><line x1=\"10\" y1=\"2\" x2=\"2\" y2=\"10\"\/><\/svg><\/div>\u00c9viter la vitre anti-UV des cadres photo<\/div>\n <\/div>\n <\/div>\n <div class=\"tip\"><strong>Pression :<\/strong> utiliser un cadre presse photographique avec ressorts, ou contreplaqu\u00e9 + pinces de serrage. Une pression insuffisante sur les bords est la cause la plus courante de vignetage.<\/div>\n <\/div>\n\n <\/div>\n\n <!-- Navigation bas -->\n <div class=\"nn-nav\">\n <button class=\"nbtn\" id=\"bprev\" onclick=\"nav(-1)\" disabled>\u2190 Pr\u00e9c\u00e9dent<\/button>\n <span class=\"nprog\" id=\"nprog\">\u00c9tape 1 \/ 4<\/span>\n <button class=\"nbtn primary\" id=\"bnext\" onclick=\"nav(1)\">Suivant \u2192<\/button>\n <\/div>\n\n<\/div>\n\n<script>\nvar cur = 0, tot = 4;\n\nfunction goTo(idx, btn) {\n for(var i=0;i<tot;i++) document.getElementById('p'+i).classList.toggle('active', i===idx);\n document.querySelectorAll('.snav').forEach(function(b){ b.classList.remove('active'); });\n (btn || document.querySelectorAll('.snav')[idx]).classList.add('active');\n cur = idx;\n document.getElementById('bprev').disabled = cur===0;\n document.getElementById('bnext').disabled = cur===tot-1;\n document.getElementById('bnext').textContent = cur===tot-1 ? 'Fin' : 'Suivant \u2192';\n document.getElementById('nprog').textContent = '\u00c9tape '+(cur+1)+' \/ '+tot;\n}\n\nfunction nav(d){ goTo(Math.max(0,Math.min(tot-1,cur+d)), null); }\n\nfunction dots(id, n, fill){\n var w=document.getElementById(id); if(!w)return;\n for(var i=0;i<n;i++){var s=document.createElement('span');s.className='rdot'+(i<fill?' on':'');w.appendChild(s);}\n}\ndots('d150',24,6); dots('d300',24,14); dots('d600',24,24);\n<\/script>\n\n<\/body>\n<\/html>\n\n\n\n<h3 class=\"wp-block-heading\"><br><\/h3>\n\n\n\n<section style=\"max-width:900px;margin:auto;font-family:system-ui,-apple-system,Segoe UI,Roboto,sans-serif;line-height:1.6;\">\n \n<h2 style=\"border-bottom:2px solid #1f4e79;padding-bottom:6px;\">S\u00e9curit\u00e9 et EPI (\u00c9quipements de Protection Individuelle)<\/h2>\n\n<p>\nLa pratique du cyanotype et de ses virages implique la manipulation de solutions chimiques. \nM\u00eame si ces proc\u00e9d\u00e9s sont consid\u00e9r\u00e9s comme relativement s\u00fbrs dans le domaine de la photographie alternative, \nil est essentiel de respecter des r\u00e8gles de s\u00e9curit\u00e9 \u00e9l\u00e9mentaires afin de prot\u00e9ger les participants et de travailler dans de bonnes conditions.\n<\/p>\n\n<h3>\u00c9quipements de protection recommand\u00e9s<\/h3>\n\n<ul>\n<li><strong>Gants en nitrile<\/strong> : prot\u00e8gent la peau du contact avec les solutions chimiques.<\/li>\n<li><strong>Lunettes de protection<\/strong> : \u00e9vitent les projections accidentelles dans les yeux.<\/li>\n<li><strong>Tablier ou blouse<\/strong> : prot\u00e8ge les v\u00eatements et limite la contamination.<\/li>\n<li><strong>Ventilation correcte<\/strong> : travailler dans une pi\u00e8ce a\u00e9r\u00e9e ou pr\u00e8s d\u2019une fen\u00eatre.<\/li>\n<\/ul>\n\n<h3>Bonnes pratiques en atelier<\/h3>\n\n<ul>\n<li>Ne jamais manipuler les produits chimiques \u00e0 mains nues.<\/li>\n<li>\u00c9tiqueter clairement toutes les solutions pr\u00e9par\u00e9es.<\/li>\n<li>Ne pas manger ni boire dans l\u2019espace de travail.<\/li>\n<li>Se laver les mains apr\u00e8s toute manipulation.<\/li>\n<li>Utiliser des ustensiles d\u00e9di\u00e9s (pipettes, b\u00e9chers, cuill\u00e8res de laboratoire).<\/li>\n<\/ul>\n\n<h3>Manipulation des solutions de cyanotype<\/h3>\n\n<p>\nLes solutions utilis\u00e9es pour le cyanotype sont g\u00e9n\u00e9ralement \u00e0 base de sels de fer. \nBien qu\u2019elles soient moins toxiques que de nombreux proc\u00e9d\u00e9s photographiques historiques, \nelles peuvent provoquer des irritations cutan\u00e9es ou des taches persistantes. \nIl est donc recommand\u00e9 d\u2019\u00e9viter tout contact direct avec la peau et les yeux.\n<\/p>\n\n<h3>Gestion des d\u00e9chets<\/h3>\n\n<ul>\n<li>Ne pas jeter de solutions concentr\u00e9es directement dans l\u2019\u00e9vier.<\/li>\n<li>Diluer abondamment les bains avant \u00e9vacuation lorsque cela est autoris\u00e9.<\/li>\n<li>Collecter les solutions contenant d\u2019autres m\u00e9taux ou produits de virage sp\u00e9cifiques.<\/li>\n<\/ul>\n\n<div style=\"background:#f4f7fb;padding:12px;border-left:4px solid #1f4e79;margin-top:16px;\">\n<strong>Rappel :<\/strong> la s\u00e9curit\u00e9 en laboratoire photographique repose sur trois principes simples : \nprotection individuelle, bonne ventilation et manipulation attentive des produits.\n<\/div>\n\n<\/section>\n","protected":false},"excerpt":{"rendered":"<p>Le cyanotype ne se limite pas \u00e0 son bleu caract\u00e9ristique. Soumis \u00e0 des bains chimiques sp\u00e9cifiques, le bleu de Prusse \u2014 pigment de coordination form\u00e9 lors de l’exposition \u2014 peut \u00eatre partiellement ou totalement transform\u00e9, substituant ses ions fer par d’autres agents complexants, ou converti en compos\u00e9s enti\u00e8rement diff\u00e9rents. C’est ce qu’on appelle le virage….<\/p>\n","protected":false},"author":1,"featured_media":4825,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_kadence_starter_templates_imported_post":false,"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"normal","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"hide","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_kad_post_classname":"","_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[150],"tags":[147],"class_list":["post-4819","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-procedes-photographiques-anciens","tag-cyanotype"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.3 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Virages du cyanotype : chimie, m\u00e9canismes et protocoles - NICOLAS LOUIS<\/title>\n<meta name=\"description\" content=\"D\u00e9couvrez comment ma\u00eetriser les virages du cyanotype gr\u00e2ce \u00e0 la chimie et aux protocoles pr\u00e9cis. 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